Urban Stream Syndrome

This is a photo of the Grinnell Natural Area during a 2004 storm event. This area is the recipient of urbanized runoff from North Berkeley, which sometimes results in localized flooding.

Most cities are not well integrated into the local hydrologic regime, and Berkeley is no exception. Fields and forests soak up rainwater like a sponge and slowly release water into streams. But with urban development, rain hits roofs, roads and parking lots and immediately gets routed away through pipes and culverts, picking up speed and pollutants as it flows downhill, and eventually dumping directly into creeks and the bay.

Common effects of urbanization on stream ecosystems are sometimes described as the "urban stream syndrome". Symptoms of urban stream syndrome include:

a flashier hydrograph (flash floods, quick pulses of water in creeks)

high concentrations of nutrients and contaminants

altered channel morphology and stability

reduced biotic richness, with increased dominance of invasive tolerant species